Hi There,
To begin or not to begin??? Hmmm ... I think it is totally up to you. There are positives and negatives on both sides. If you begin you will most likely be down a bit before you leave. That just may motivate you to stick close to plan while on vacation. It's not toooo difficult.
Just bring along your supplies and have a lean and green once a day. Being on program may even "save you" from packing on a few extra pounds that you'll have to deal with when you get back. On the other hand, it does require planning. Plus you'll have to monitor yourself a bit. That's not a bad thing.
Think about it and see if you think you can enjoy your vacation while being careful about what you eat. I actually think it just may be a great learning experience for you. We all need to learn that we can have a great time without munching everything we see.
Another option you may be considering is to start program, go on vacation, eat and then restart when you get back. This is generally not the best option since it requires renewed dedication and another three days for your body to readjust. Some people have great difficulty getting going again. That's the greatest hazard.
jan